Tip of the iceberg: What’s WNC’s true rate of COVID-19?

Blood donor with the American Red Cross
POWER IN THE BLOOD: COVID-19 antibody testing of blood donors may help public health officials understand the true prevalence of the disease. Photo by Dennis Drenner, courtesy of the American Red Cross

The labs have been busy these days: Both locally and across the state, viral tests are confirming ever more cases of COVID-19. In the week between June 29 and July 6, Buncombe County recorded 111 new cases of the disease, a number that took nearly two months to reach after the county’s first contact with the coronavirus. North Carolina’s new daily case count exceeded 2,000 for the first time on July 3.

But beneath those lab-confirmed cases likely lurks a much larger group of people who have contracted the virus without ever knowing it. Dr. Robert Redfield, director of the federal Centers for Disease Control and Prevention, said on June 25 that his team estimates 10 additional coronavirus infections for each reported case of COVID-19. Many of those undetected cases are asymptomatic, so those infected are likely to interact with others and potentially spread the virus.

The CDC’s estimate is based on testing a broad sample of the population for antibodies to the coronavirus. Because the human immune system makes antibodies in response to viruses even in the absence of symptoms, and those antibodies linger in the blood for some time after infection, antibody tests can show if someone had the coronavirus after the fact.

Although the CDC tested nearly 12,000 people to draw its conclusions, those samples came from just six regions of the U.S., with Missouri the closest area to Western North Carolina. Xpress sought to determine if a similar pattern of hidden cases might hold true for the area’s coronavirus infections.

Not my job

Local health departments, however, didn’t have much to say on the subject. “Antibody testing is not reportable,” said Buncombe County Health and Human Services spokesperson Stacey Wood in response to a June 29 information request.

Officials with the Henderson County Health Department echoed that response, saying they had not received antibody test results at the local level. Steve Smith, the department’s health director, added that such information likely wouldn’t help his team in its day-to-day work of contact tracing and public health promotion.

“The results would probably be used only for the purpose of prevalence estimation in communities,” Smith explained. “Since a positive antibody test doesn’t equate to immunity, it doesn’t have immediate or practical value for us with communicable disease control measures at the county level.”

State-level responses provided little more detail. According to Kelly Haight Connor, a spokesperson for the N.C. Department of Health and Human Services, the state is not currently gathering antibody testing data and has yet to use that information as part of its regular disease analysis. “DHHS is assessing options for routinely collecting these results and integrating them into our COVID-19 surveillance,” she said.

In response to an Xpress question at a July 2 press conference, DHHS Secretary Dr. Mandy Cohen said her department had looked at preliminary coronavirus antibody results collected by the state’s research community. A study by Wake Forest Baptist Health, she said, had reported antibody levels of around 10%, while other studies found levels in the range of 5%-6%. She did not specify if any of those studies had been conducted in WNC.

“What it’s telling us is that there’s virus here, and there’s a lot of folks that have been exposed to COVID-19 here in North Carolina. That shows you that there is a lot of spread of this virus when people don’t even know that they are sick,” Cohen said.

Blood will out

While Cohen mentioned scientific work, some of the biggest coronavirus antibody testing efforts in North Carolina are being conducted by nonprofit organizations. Both the American Red Cross and The Blood Connection currently offer free antibody tests for all blood donors, who gain access to their results as a reward for their generosity.

Yet the blood banks have been reluctant to publicize their findings. Maya Franklin, a spokesperson for the Red Cross, said her organization would only provide data to state health departments, not media outlets or the public.

Connor with NCDHHS confirmed that the state had been in touch with the Red Cross but said her department had not yet received the nonprofit’s aggregate data. A July 1 records request for recent correspondence between state health officials and the Red Cross had not been fulfilled as of press time.

Meanwhile, The Blood Connection initially declined to share its antibody test numbers and positivity rates, citing patient privacy requirements under the federal Health Insurance Portability and Accountability Act. Reminded that HIPAA only applies to identifiable health information and not bulk testing results, spokesperson Heather Moulder said her organization had “been overly cautious” and provided data for the period from May 11 through June 25.

Moulder said The Blood Connection had analyzed nearly 32,000 units of blood for coronavirus antibodies across all of its 10 donation centers. Positivity rates were 1.5% for 1,825 units in Buncombe County, 1.4% for 1,465 units in Henderson County and 1.33% for 18,776 units across all of North Carolina.

Moulder emphasized that this data set was insufficient to draw definitive conclusions, and tests can also yield positive results for people who previously have been infected with a different coronavirus. But even taken as rough estimates, the antibody numbers suggest that official Buncombe and Henderson COVID-19 case counts may capture only a fraction of those infected.

By June 25, Buncombe County had 523 lab-confirmed cases of COVID-19. If 1.5% of Buncombe’s roughly 261,000 residents had been infected, the true case count as of that date would have exceeded 3,900 — nearly 7.5 times the lab-confirmed count.

On the same date, Henderson County had 581 confirmed COVID-19 cases. Assuming a 1.4% prevalence rate across the county’s population of about 117,400, the true case count as of June 25 would have been about 1,640, or a little less than triple the number of reported cases.

Testing, testing

As it becomes increasingly clear that COVID-19 will be with North Carolina for the long haul, more formal antibody testing efforts are gearing up throughout the state. On July 7, Sen. Thom Tillis announced that Wake Forest Baptist Health had received a $27 million contract from the CDC to conduct a “broad-based antibody population surveillance study.”

Locally, according to Connor with NCDHHS, the UNC Gillings School of Global Public Health has proposed an antibody study with the Asheville-based Mountain Area Health Education Center to be conducted in Buncombe and Henderson counties. Dr. Allison Aiello, a disease expert with UNC, says the work is still in the planning phase and will be led by MAHEC researchers.

However, the status of that work remains uncertain. Dr. Susan Mims, chair of the Department of Community and Public Health at MAHEC, said her organization was not conducting any antibody studies but is “reviewing several.” Spokesperson Jennifer Maurer could not confirm by press time whether MAHEC planned to collect new antibody data in the future or would limit itself to review of existing information.

Mims did note that MAHEC is active in other parts of the region’s COVID-19 response. “We are working closely with UNC Asheville on a project to support the six regional residential colleges and universities on their reopening strategies,” she explained. “Our Community Response Team at MAHEC is also collaborating with health care organizations, practices, and others to address and mitigate the effects of COVID in Western NC.”

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About Daniel Walton
Daniel Walton is the Assistant Editor of Mountain Xpress, regularly contributing to coverage of Western North Carolina's government, environment and health care. His work has previously appeared in Capital at Play, Edible Asheville, and the Citizen-Times, among other area publications. Follow me @DanielWWalton

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